Question

According to the WHO MONICA Project the mean systolic blood pressure for people in China is 128 mmHg with a standard deviation of 23 mmHg (Kuulasmaa, Hense & Tolonen, 1998). Systolic blood pressure is normally distributed. a.) TRUE or FALSE: The random variable is defined as systolic blood pressure of a person in China. b.) For a sample of size 15, state the mean of the sample mean. c.) For a sample of size 15, state the standard deviation of the sample mean (the "standard error of the mean"). d.) Suppose a sample of size 15 is taken. Find the probability that the sample mean systolic blood pressure is more than 135 mmHg.

Answer 1

Solution:

Given that,

= 128

= 23

n = 15

So,

= 128

a ) True.

b ) =  ( / )

c )   = (23 / 15 )

d ) = 5.9386

p (   > 135)

= 1 - p (   < 135)

= 1 - p ( - /) < (135 - 128 / 5.9386 )

= 1 - p ( z < 7 / 5.9386 )

= 1 - p ( z < 1.18)

Using z table

= 1 - 0.8810

= 0.1190

Probability = 0.1190